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Water Colors（2）
Western U.S. river colors mostly moved toward the blue end of the spectrum over time, suggesting they carried less sand and silt. But many rivers in the Northeast showed a “redshift” that made them appear more yellow, indicating lower water levels or increasing sediment. Gardner says this divergence suggests that regional factors, such as land-use patterns and watershed-management practices, influence long-term river hue shifts. (Some rivers shifted against these trends because of local influences.)
随着时间的推移，美国西部河流的颜色大多趋向于波谱的蓝色一端，说明它们携带的沙石和淤泥较少。但东北部许多河流呈“红向移动”，视觉上看起来更黄，说明其水位降低或沉积物增加。加德纳说，这种差异体现了区域因素，如土地利用模式和流域管理实践，会影响长期河流色调变化。（一些河流由于当地影响，与上述变化趋势相反。）
“We also found very distinct seasonal patterns,” Gardner says. Many of the nation’s rivers turn yellower in spring or summer as peaking rainfall muddies the waters. But the timing also depends on geography and on human activity such as agriculture.
加德纳说：“我们还发现了非常明显的季节性模式。”随着春夏季降雨量达到峰值，水域会变得浑浊，美国的许多河流在这一时期也会变黄。但具体时间也取决于地形和农业等人类活动。
Using satellites to gauge changes in river composition could warn scientists when environments begin to fall out of balance, the researchers say. Legleiter is particularly interested in watching for harmful algal blooms. “A lot of times with environmental change, we don’t see it until too late,” O’Reilly add. “But with satellites, we could start to see changes early on.”
研究人员表示，当环境开始失去平衡时，利用卫星来判断河流成分的变化可以给予科学家警示。勒格莱特对观察有害藻华特别感兴趣。“很多次河流成分随着环境变化，我们发现的时候已经太晚了，”奥莱利补充道，“但是有了卫星，我们可以提前看到这些变化。”
【积累表达】
fall out of balance 失去平衡
【重点词汇】
divergence n.分歧，差异
hue n.色彩，色度；叫声
timing n.时机；定时；时间设置
gauge v.估计，判断；计量，度量
Western U.S. river colors mostly moved toward the blue end of the spectrum over time, suggesting they carried less sand and silt. But many rivers in the Northeast showed a “redshift” that made them appear more yellow, indicating lower water levels or increasing sediment. Gardner says this divergence suggests that regional factors, such as land-use patterns and watershed-management practices, influence long-term river hue shifts. (Some rivers shifted against these trends because of local influences.)
随着时间的推移，美国西部河流的颜色大多趋向于波谱的蓝色一端，说明它们携带的沙石和淤泥较少。但东北部许多河流呈“红向移动”，视觉上看起来更黄，说明其水位降低或沉积物增加。加德纳说，这种差异体现了区域因素，如土地利用模式和流域管理实践，会影响长期河流色调变化。（一些河流由于当地影响，与上述变化趋势相反。）
“We also found very distinct seasonal patterns,” Gardner says. Many of the nation’s rivers turn yellower in spring or summer as peaking rainfall muddies the waters. But the timing also depends on geography and on human activity such as agriculture.
加德纳说：“我们还发现了非常明显的季节性模式。”随着春夏季降雨量达到峰值，水域会变得浑浊，美国的许多河流在这一时期也会变黄。但具体时间也取决于地形和农业等人类活动。
Using satellites to gauge changes in river composition could warn scientists when environments begin to fall out of balance, the researchers say. Legleiter is particularly interested in watching for harmful algal blooms. “A lot of times with environmental change, we don’t see it until too late,” O’Reilly add. “But with satellites, we could start to see changes early on.”
研究人员表示，当环境开始失去平衡时，利用卫星来判断河流成分的变化可以给予科学家警示。勒格莱特对观察有害藻华特别感兴趣。“很多次河流成分随着环境变化，我们发现的时候已经太晚了，”奥莱利补充道，“但是有了卫星，我们可以提前看到这些变化。”
【积累表达】
fall out of balance 失去平衡
【重点词汇】
divergence n.分歧，差异
hue n.色彩，色度；叫声
timing n.时机；定时；时间设置
gauge v.估计，判断；计量，度量
